Expansion means of treble booms for use with a crane truck



p 1969 SHINITSU SHINOHARA ET AL 3,468,431

EXPANSION MEANS OF TREBLE BOOMS FOR USE WITH A CRANE TRUCK Filed July 19. 1967 M M mum WM M g ,M Hu 3 Nm 9 m Hr. F M .7 i H a w/ 5 H. n .J/ u fi 5 5% o A 5 Z i Q 2 1 fi x F A rrun/t I! United States Patent U.S. Cl. 212-55 1 Claim ABSTRACT OF THE DISCLOSURE This invention discloses treble booms consisting of three boom members which are telescopically inserted one after another, and having a primary hydraulic hoist provided outside the booms and connecting the first two boom members to extend or telescope them and a secondary hydraulic hoist provided inside the booms and connecting the last two boom members to extend or telescope them. Said primary and secondary boom members are hydraulically interconnected each other by a single hydraulic fluid system connecting the chambers of the primary hydraulic hoist, two fluid passages provided in a piston rod of said hoist and respectively opened to one of said chambers, two fluid passages provided between the first two boom members and respectively communicating with one of the firstly-mentioned fluid passages of the piston rod of the primary hydraulic hoist, and two chambers of the secondary hydraulic hoist respectively communicating with one of the secondly-mentioned fluid passages.

Background of the invention It is generally known that treble or three-section booms mounted on a truck as part of a mobile crane have to be expansible structures. However, with such expansible booms, constructed to be expanded with only a double-acting multi-stage hydraulic pressure actuator, not only is the cost very great but also the weight of the boom is very great. This is particularly true when such a boom is expanded by a unit extension of each of its movable sections, with the elevating of the boom being effected by a hydraulic pressure actuator supported at only two points, namely the outer end of a piston rod and the base of the associated cylinder. The arrangement is not practical because of the increasing weight and size if the boom is provided with suflicient resistance to buckling. When the members of the boom are decreased in diameter, it is difficult to make the walls sufficiently thick to resist the double-acting multi-stage hydraulic pressure within the boom and provide suflicient buckling strength.

On the other hand, if a single-acting hydraulic pressure hoist is arranged between each pair of sections of the boom, so that each section can be expanded relative to another section, other problems arise, such as how the hydraulic pressure hoist should be arranged and in what way the secondary hydraulic hoist, which moves with the expansion boom, should be supplied with working fluid.

The object of this invention is to solve each of said problems and to provide an expansion means comprising treble booms and having novel advantages where the length of each boom is particularly long or the diametral size of the expansion boom member is small in comparison with its length.

Namely the expansion means of treble booms according to this device comprises; the expansion boom member being constructed by insertedly securing and slidingly mounting a cylindrical intermediate boom member and a top end boom member into a cylindrical base boom 3,468,431 Patented Sept. 23, 1969 'ice one after another telescopically, a spacial gap formed to lay two hydraulic passages particularly between the inside of the base boom member and the outside of the intermediate, the primary hydraulic pressure hoist in a desirable position of their outside between the base boom member and the intermediate, the secondary hydraulic pressure hoist in a desirable position of their inside between the intermediate boom member and the top end, two hydraulic passages being formed in a piston rod of the primary hydraulic pressure hoist, each outer end of the piston of said hydraulic passages being opened to a cylinder chamber at both sides of each piston, its other end being connected with two hydraulic passages laid by the intermediate boom member in the spacial gap be tween the base boom member and the intermediate, working oil of the secondary hydraulic pressure hoist being supplied through hydraulic passages in said piston rod and hydraulic one laid in the spacial gap.

In order to facilitate an understanding of the device, reference is made hereinto an embodiment illustrated in the accompanying drawings.

In the accompanying drawings:

FIG. 1 is a side view showing an embodiment of the present invention device;

FIG. 2 is a plan view of FIG. 1 with a part cut open;

FIG. 3 is a magnified view of a longitudinal section taken on the line IIIIII of FIG. 1;

FIG. 4 is a longitudinal side view of a primary hydraulic pressure hoist.

Numeral 1 indicates a turning bed secured on a chassis 2 of a truck body, and an expansion boom member A, elevatable by operation of hoist 5, is pivoted at 4 at the starting portion of its base boom member 3, to the upper portion of the turning bed 1. Expansion boom member A comprises a cylindrical intermediate boom member 6 and a top end boom member 7 which are inserted in the outer base boom member 3 thereof and mounted slidingly one after another telescopically. However in the expansion boom member A according to this invention a spacial gap, portion to secure and lay two hydraulic passages 8, 9 at the side of intermediate boom member 6, is formed particularly between the right inside 3a of the base boom 3 and the right outside 6a of the intermediate 6.

Illustrated at 10 is a linear hydraulic pressure actuator including a cylinder 10a and a piston 10b. The end of cylinder 10a is pivoted at 11 to the base or outer boom section 3, and the outer end of piston 10b is pivoted at 12 to the outer end portion of intermediate boom member or section 6. A second linear hydraulic pressure actuator 13 is connected between intermediate member or section 6 and outer boom member or section 7. Actuator 13 includes a cylinder 13a which is pivotally connected, at 14, to the interior of the inner end of intermediate boom section 6. Actuator 13 further includes a piston rod 13b having its outer end connected to outer boom member or section 7 adjacent the outer end of the latter.

Fluid flow passages are formed in actuator 10, and comprise concentric passages 16 and 17 in piston 10b. Passage 16 opens through a wall 20 into a chamber 19, adjacent the inner surface of a piston 18, chamber 19 being formed between piston rod 10b and cylinder 10a. Passage 17 opens, at 22, through piston 18 to hydraulic chamber 21 in cylinder 10a, chamber 21 being adjacent the outer surface of piston 18. At the outer end of piston rod 10b, fluid flow passages 16 and 17 communicate, at pivot 12, with the hydraulic conduits 8 and 9 positioned in space 0 between boom member 3 and boom member 6. Hydraulic conduit 8 is connected to a hydraulic chamber (not shown) adjacent the piston rod side of the piston of hydraulic cylinder 13a, and hydraulic fluid conduit 9 is connected to another hydraulic chamber (not illustrated) 3 adjacent the opposite surface of this piston of cylinder 13a.

Working fluid is supplied through inlet and outlet openings 23 and 24 into the chambers 19 and 21, respectively, on opposite sides of the piston 18 of actuator 10. The working fluid not only operates piston 18 but also, through passages 16 and 17 in piston rod 1% and conduits 8 and 9 in space 0, operates actuator 13.

The expansion means according to this invention constructed as above mentioned operates so that when working oil is supplied through oil supply opening 24 into the hydraulic chamber 21 opposite the piston rod of the hydraulic pressure hoist 10, both hydraulic pressure hoists 10, 13 are expanded so as for expansion boom member A to expand and on the contrary when working oil is supplied through oil supply opening 23 into the hydraulic chamber 19 by the piston rod of the hydraulic pressure hoist 10, both hydraulic pressure hoists 10, 13 are contracted so as for expansion boom member A to reduce in length.

Thus in the means according to this invention in which oil supplied into the hydraulic pressure hoist 13 moving with the intermediate boom member in a body is performed without using a flexible pipe, so that the expansion means of treble booms according to this are not only of very good design but hydraulic actuators 10, 13 arranged in each of boom as above mentioned, are endowed with the suflicient buckling strength and besides can be produced light in weight and inexpensively, the means according to this invention are very suitable particularly in the case when the amount of expansion is maximized or the diametrical size of each boom is arranged small in comparison with its length.

What is claimed is:

1. A mobile crane comprising, in combination, a mobile crane truck; an extensible boom pivotally mounted, adjacent its inner end, on a support on said truck; a hydraulic hoist connected between said support and said boom to raise and lower said boom; load supporting means mounted on the outer end of said boom; said boom having three rectangular tubular cross section boom members constituted by an outer base member, an intermediate member slidable within said base member and an end member slidable in said intermediate member; said base member being pivoted to said support and connected to said hoist, and said end member carrying said load supporting means; the spacing of one lateral wall of said intermediate member from the adjacent lateral wall of said base member being greater than the spacing of the opposite lateral wall of said intermediate member from the opposite lateral Wall of said base member and greater than the spacing of the other two lateral walls of said intermediate member from the adjacent lateral walls of said base member and the spacing of the lateral walls of said intermediate member from the lateral Walls of said end member, whereby to provide, between said one lateral wall of said intermediate member and the adjacent lateral wall of said base member a space extending longitudinally of said beam; a pair of hydraulic fluid conduits extending longitudinally of said space; a first linear hydraulic actuator including a cylinder connected at its inner end to said base member adjacent the inner end of said base member, a first piston in said cylinder and a first piston rod connected to said piston and having its outer end connected to said intermediate member adjacent the outer end of said intermediate member; a pair of hydraulic fluid passages extending longitudinally through said first piston rod, the inner end of one of said passages communicating with said first cylinder between said first piston and the inner end of said first cylinder, and the inner end of the other passage communicating with said first cylinder adjacent the opposite side of said first piston; the outer end of each hydraulic fluid passage being connected to and communicating with a respective one of said hydraulic fluid conduits; and a second linear hydraulic actuator mounted interiorly of said intermedi ate and end boom members, said second actuator including a second cylinder connected at its inner end to the inner end of said intermediate member, a second piston in said second cylinder, and a second piston rod connected to said second piston and connected at its outer end to said end boom member adjacent the outer end of said end boom member; said second piston defining, in said second cylinder, first and second chambers on opposite sides of said second piston; one of said chambers communicating with one of said hydraulic fluid conduits and the other of said chambers communicating with the other of said hydraulic fluid conduits, at the ends of said hydraulic fluid conduits opposite to those ends of said hydraulic fluid conduits connected to said hydraulic fluid passages; and a pair of hydraulic fluid inlet and outlet passages each communicating with said first cylinder on opposite sides of said first piston.

References Cited UNITED STATES PATENTS 3,212,604 10/1965 Garnett 212- 3,243,052 3/1966 Grove 212-55 FOREIGN PATENTS 418,560 8/1966 Switzerland.

GERALD M. FORLENZA, Primary Examiner RAYMOND B. JOHNSON, Assistant Examiner 

